


Clathrus Archeri

by CielPansyhive



Category: Kuroshitsuji | Black Butler
Genre: Adult Ciel Phantomhive, Alternate Universe - Canon Divergence, Anal Fingering, Anal Sex, Biting, Blood Drinking, Demon Dick, Demon Heat, Demon Sex, Feathers & Featherplay, M/M, Oral Fixation, Oral Sex, SebaCiel - Freeform, Size Difference, Smut, blooming dick, cumming untouched, not knotting but close
Language: English
Status: Completed
Published: 2019-06-05
Updated: 2019-06-05
Packaged: 2020-04-08 02:27:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,902
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19097878
Author URL: https://archiveofourown.org/users/CielPansyhive/pseuds/CielPansyhive
Summary: Sebastian requests a week off of his butler duties to resolve a 'problem.' Ciel is supposed to stay away for that week, but where is the fun in that?Demon smut written for 'Devil's Day.'





	Clathrus Archeri

**Author's Note:**

> Thank you for reading, please kudo and comment!  
> I'm really happy with how this turned out, so I'm posting it early!  
> I was inspired by the fungus known as 'devil's fingers.' Though I made a few changes for it to be a bit more appealing.  
> Feel free to follow me: https://cielpansyhive.tumblr.com/

“You need a week off? Whatever for?” Ciel blinked his bright sapphire eye. Never in all the years of their contract had Sebastian asked for time off. Sebastian shifted his weight from one foot to the other in an almost impatient manner. Ciel noted the little beads of sweat gathering on Sebastian’s forehead. “You’re not sick are you? I didn’t think demons were prone to illness.”

“I’m not ill,” he snapped. His gaze fell to the floor and his shoulders slumped. “I do apologize for my outburst. I’m not myself right now, or rather I am too much myself.”

“What’s with you?” he crossed his arms and scowled. “Out with it, I have no time for riddles.” Sebastian chuckled, bright red eyes slowly came to rest on his master once more.

“And I, no time for games,” he sighed. “As you know most of my contracts don’t last near as long as this one has.”

“You’re hungry aren’t you? You’re tired of waiting to consume my soul,” Ciel guessed.

“You are worth the wait master,” Sebastian smiled sincerely. “It is...a kind of a hunger, one most demons go through every few years or so.”

“Well as long as it doesn’t involve me, go take care of your demon thing,” he waved his hand to shoo Sebastian away. “The sooner you take care of it, the sooner I have my butler back.”

“Ah, you see master, it’s not that simple. This hunger is more carnal in nature, controlled by hormones for the preservation of demons.”

“Like a dog,” Ciel smirked.

“No,” Sebastian grumbled. “It’s a demon thing.”

“So what, do you need a hell pass? Or will one of the local human prostitutes work for you?” Sebastian marched up to Ciel’s desk and slammed his palms down, the vibration knocking multiple items to the ground.

“This isn’t a joke Ciel!” he yelled. “While I am bound to you, you are my only suitable mate,” the purple glow of the contract mark bled through the white gloves. Ciel’s eye thrummed distressingly, he pressed his hand to it hoping it would ease the sensation. “When I am like this you are in danger,” he spoke softer as he backed away slightly. “As you can see, my control is already slipping.” Ciel gulped and nodded, hand still pressed to his eye.

“So a week?”

“Yes, I’ll lock myself away in the furthest guest room. I can’t be near you like this. It’ll only get worse each day.”

*

The next few days were quiet without Sebastian’s commentary on everything. All the servants were on their best behavior knowing Sebastian wasn’t there to bail them out of trouble. _I should send Sebastian away more often, I don’t think any of them have ever worked this efficiently_ , Ciel thought. He tossed and turned in bed unable to get comfortable or silence his mind. It wasn’t that he missed his butler. He missed the routine and familiarity, that’s all. _Maybe I can just visit outside of the room._ He got up and tip toed his way to the far end of the hallway. As he came closer to the door he felt a wave of heat. He heard scratching, deep groans, and wings beating. He carefully lowered himself to the keyhole to peer through. He couldn’t see much in the dark besides an eerie red glow. All movement stilled.

“Ciel,” Sebastian whispered, voice beckoning him to open the door. “I know you’re there.” Ciel stammered as he stood upright, feeling like a right pervert for spying.

“I-I, sorry I’ll leave,” he placed his hand against the door not wanting to go back just yet. Claws tapped on the other side of the door. A low, tempting moan replied.

“Don’t go,” Sebastian’s voice dripped like honey. “Join me.” Ciel closed his eyes and let his head softly hit the door. He swore he could feel the hot breaths penetrate the heavy door.

“You know I can’t, you warned me.”

“I’ll make it worth your while,” Sebastian’s words nipped at his ears, pulled at something deep inside of him.

“Fuck,” alarm bells were going off in Ciel’s head but he chose to ignore them. The sweet call of his demon was too much. As soon as he entered the sweltering room the door slammed shut. He was then roughly pressed against a wall by an unseen force. Sebastian stepped into view illuminated by the red glow of multiple eyes on his forehead, chest, shoulders; even the back of each hand had one. He gave a sharp tooth-filled smile. Mouth cut from pointed ear to ear.

“Ah, my little lord has come to play,” his clawed charcoaled hands gripped Ciel’s shoulders. Far too massive to be human, they belonged to a beast. His skin looked as if he rolled about in the fireplace, matching the intense aura that permeated the room. His wings feathered in the blackest of black that lacquered his horns as well. He looked nothing like the butler of Phantomhive and everything like the hell spawn he truly was.

“H-how are you, Sebastian?” Ciel was lifted like a ragdoll and carried to the bed. Had Ciel not been quite as terrified he would have expressed disappointment that Sebastian lacked a spade tipped tail that many of his books depicted devils having. He was tossed onto the torn sheets. His own nightshirt was ripped to ribbons seconds later. He took note that the headboard was scratched and nicked beyond repair and would need replacing after it was all over.

“I’m ravenous,” a forked tongue peaked out to lick his lips. He took in the smooth ivory skin of his master, wanting to litter it with violets and crimson. Make his claim so all would know. His eyes cast a warm glow, enhancing Ciel’s already flushed body. His wings beat powerfully over them. Ciel went to reach for them but Sebastian pinned his wrists with one hand. “You made me wait,” he tilted his head to the side, much like a bird would when trying to understand something.

“You told me to, I-I wasn’t even supposed to-“ Ciel wanted to roll his eyes, though he dare not upset the beast that could easily break the fragile wrists in his clutches.

“I should punish you,” Sebastian grinned. He plucked a pitch black feather from his wings. “See how you like it.” He traced the feather across Ciel’s clavicles, down his sternum to his thin belly, then back up his chest catching on his nipples. Ciel tensed his arms, lean muscles flexing.

“Sebastian!” Ciel squirmed as his dotted flesh rose. His hard cock leaked on his pale stomach. He wiggled his hips trying to find something to grind on. Sebastian brought the feather down to the weeping member. The feather soaked up the sticky fluid as it tickled the twitching organ. “Mmhmm, Se-Sebastian,” he panted. The feather went lower, caressing his sack and teasing his taint. Ciel tried to follow the movements of the feather but was distracted by what was between Sebastian’s legs. The deep scarlet head was tapered, the shaft brighter red and girthier as it neared the base. Four or five almost invisible seams ran along the whole length. Something dark and thick dripped from the tip. Sebastian noticed the drift of attention by the less urgent bucking of hips. He abandoned the feather and straddled Ciel’s chest, still keeping the slender wrists bound in his grasp.

“Want a taste my lord?” Ciel hesitantly stuck his tongue out as more of the syrupy liquid leaked. It looked like the rich, dark chocolate ganache he enjoyed so much, though it certainly didn’t taste like it. The bitterness burned to the back of his throat. He didn’t have time to cough before Sebastian shoved himself in. The rough texture was oddly satisfying as the shaft scraped at his tongue, neutralizing the bitterness coating his mouth. He groaned around the girth stretching his lips, it pulsed and thickened with every thrust. Sebastian pulled out, dark sepia dribbled onto Ciel’s face. The seams that decorated his dick were now gaps in the much fuller member. Ciel was flipped onto his stomach and his wrists were finally released. Sebastian dug his claws into the plump cheeks as he parted them. Forked tongue slithered over the pink hole, dipping in just enough to tease. Ciel tried to push himself back only for Sebastian to remove himself. “Open yourself up for me,” Sebastian purred. He clumsily swiped at a vile on a nearby end table, knocking it onto the bed. Ciel picked it up and slathered the oil over his fingers. He rested his weight on one arm as his other hand found his entrance. Not wasting any time he plunged two fingers in, groaning at the intrusion. He wiggled them, brushing against a bundle of nerves.

“Ahh,” he shook as he kept stroking that spot that made fire pool in his belly. He started scissoring them and pumping in and out. Sebastian bit into the soft flesh of his ass, blood bubbled up from the little puncture marks. Sebastian happily licked at the wound and proceeded to make a few more. Ciel slipped in a third finger, he moaned into the mattress. His face dusted with blush over how lewd he must look. Sebastian lapped at the tight rim and fingers. He removed the dainty fingers belonging to his master and sucked on them. He rut his cock between the abused cheeks. As it became more engorged it opened further, much like a flower blooming. He held it steady as he stuffed himself inside Ciel.

“Master!” he whined as he pistoned his hips, quite literally fucking Ciel into the mattress. Every push was a little rougher. A few pairs of eyes closed in pleasure. Sebastian dug his claws into the mattress, too worried what would happen if he held on to Ciel. He’d rather him be skewered on his cock, not his hands. As he opened up more he found it increasingly difficult to fit his entire member in Ciel. He let out a howl of frustration.

“Se-Seb-astian,” Ciel rasped. Sebastian tried to control his hips in a slow roll. “U-up! L-let me sit in y-your lap.” Sebastian sat up and brought Ciel with him, keeping himself buried as deeply as possible. With the help of gravity Ciel was impaled another inch. “Oh fuck!” he reached his shaking hands up and took a horn in each. Ciel’s mind went blank as his guts were pressed into. Sebastian’s wings flapped excitedly as his partner threw his head back. Ciel’s jaw dropped as his sensitive walls were stretched. Sebastian forced the remainder of his girth in and bit Ciel’s shoulder to stifle his deep growl. He drank in the sweet blood of his master. Ciel swiveled his hips and gasped. He clenched around Sebastian, trying to suck him in deeper. He wailed and yanked on Sebastian’s horns as he released all over his chest and stomach. His whole body trembled and jerked with aftershocks. Sebastian soon followed emptying hot load after load into Ciel. Ciel’s eyes rolled back as he collapsed against Sebastian. His arms dropped to his sides still shivering. Sebastian nuzzled into his neck purring and let his wings wrap around them both. The room darkened as he shut all of his eyes.

“Four more days of this my lord,” he chuckled. “I did warn you.”


End file.
